Protein G is a surface protein of two groups of streptococcal bacteria that has ability to bind immunoglobulins and also to albumins. Protein G are prepared from chromatographically pure protein G.

Protein G is stable at 4 °C as an undiluted liquid. Freezing alkaline phosphatase conjugates will result in a substantial loss of enzymatic activity.

Protein G alkalline phosphatase conjugated is ideal for signal transduction, molecular biology, cancer, and cell signaling. Protein G peroxidase conjugated is a useful reagent in western blotting and ELISA experiments. Protein G fluorescein conjugated is suitable for immunomicroscopy and flow cytometry or FACS analysis.